Precious can be a shock if you pull it first. It does a Mortal Strike, stacking very quickly. The zombies are summoned each time he howls, spawning in a circle around Precious. Tanks should taunt Precious around every five stacks of Mortal Strike.

After the hound is dead, the zombies will not despawn. Players should keep kiting - using snares, paladin Holy Wrath, etc. Zombies will place a stacking debuff on any raid members they strike.

An alternative way to handle zombies is to have everyone collapse on the boss and set up an AoE kill zone.